When coalition pilots penetrated Syrian airspace early Tuesday morning, it was unclear if they would just strike Islamic State targets or clash with the Syrian regime. Though Syria was warned prior to the attack, it was unclear if Bashir al-Assad would follow through on his threat to consider any operation in Syria as an act of aggression. In fact, there are clues that coalition planners were prepared for a Syrian military response.

First Wave

Around 3:30 am Syria time, the destroyer USS Arleigh Burke in the Red Sea and the cruiser USS Philippine Sea in the Persian Gulf launched a salvo of 47 Tomahawk missiles towards northwestern Syria. Their targets were al-Qaeda operatives west of the contested city of Aleppo. Apart from maybe a few MANPADS, the group had no serious air defense. Nevertheless, in the opening shots of this air campaign, U.S. war planners chose to launch long-range cruise missiles costing $1.4 million each.

The choice of Tomahawks, which have a poor track record of killing terrorist groups, likely indicated concern about Syria’s air defenses. To target al Qaeda in western Syria with manned aircraft could have proved hazardous. Western Syria is a hornet’s nest of Syrian surface-to-air missiles (SAMs).

If the goal was to hit al Qaeda targets while also testing Assad’s response, the use of Tomahawk missiles was a logical step. With sophisticated signals intelligence aircraft, airborne early warning aircraft, and reconnaissance drones circling near or above Syria, U.S. commanders would have been able to see the regime’s reaction to the barrage of Tomahawks and subsequently determine whether non-stealthy manned fighter aircraft could penetrate Syrian airspace unchallenged.

Second Wave

A half hour after the first wave, the U.S. ordered its stealthy F-22 Raptors into the air, accompanied by non-stealthy B-1B bombers, multirole F-15E and F-16 fighters, and unspecified armed drones from multiple air bases throughout the region. These air bases included:  al Arzraq and Mafraq in Jordan, al Dhafra in the UAE, and al Udeid in Qatar. Meanwhile, a coalition of Arab air forces also launched aircraft to participate in this unique operation. According to reports, at least four Saudi F-15S strike fighters, four F-16E/F multirole fighters from the UAE, four Jordanian F-16AM/BM fighters, two Bahraini F-16C/D fighters, and two Qatari Mirage 2000 French-built fighters participated (only the UAE was in the second wave, the rest came in the third). Because most of the aircraft are American-made and armed with U.S. munitions, they integrated easily with U.S. air assets.

American F-22s, in their first combat mission ever, struck targets near Raqqa in central Syria. The Pentagon’s deployment of this aircraft may also point to U.S. concerns over a confrontation with Assad. These pricey stealth fighters, while perfectly capable of conducting ground strikes, were primarily designed for air superiority missions. Since becoming operational in 2005, the F-22 has been benched by commanders because the majority of U.S. conflicts have not necessitated a high-end aircraft to tangle with an opposing air force. For strikes against a poorly armed terrorist group like the Islamic State, older and less expensive aircraft like the F-15 and F-16 could have easily accomplished the task. But like the decision to open with Tomahawk missiles, commanders appear to have opted for their dominant fighter jets for safety’s sake — to operate closest to where Syrian air defenses are stationed. If at the opening of the second wave the Syrian air defenses turned on, the stealthy raptors could have evaded fire and shielded the rest of the coalition force from any Syrian MiG-29s, 25s or 21s deployed to oppose them.

Third Wave

Three hours later, the third wave of U.S. and coalition aircraft begin striking targets in eastern Syria. This is also where the majority of non-stealthy aircraft appear to have operated – far from Assad’s air defense in the west. This wave included carrier based F/A-18s and U.S. Air Force F-16s, as well as the majority of the Arab aircraft.

Another clue that the U.S. flew into Syria unsure of a confrontation with Assad comes in the form of a video released by Central Command showing U.S. F-16s refueling during strikes in Syria. These multirole fighters were fully armed with a range of precision guided bombs and air-to-air missiles. One F-16 was even armed with an AGM-88 HARM missile, designed to home in on enemy radars and largerair defense systems, not the handful of MANPADS possessed by jihadist groupsin Syria.

In all, with 160 munitions used and only 22 ISIS targets hit, the large amount of aircraft deployed would seem unnecessary. In fact, the two Qatar Mirages reportedly did not even strike any targets. However, as Pentagon officials mentioned, some of the aircraft served in combat air patrols prepared to respond to challenges by the Syrian regime. The large contingent of aircraftwould be visible to Syrian radar, providing an additional deterrent against challenges from the Syrian regime.

Multiple questions remain as to whether this campaign will be effective if the U.S. and partners must continue to take such measures for fear of skirmishes with Damascus. If this is a prolonged effort, as the Pentagon claims, it seems inevitable that the US and its partners will be operating in close proximity to Syria’s Russian and Iranian-backed military. The likelihood of contact will increase over time. The only way to avoid this contact would be to limit strikes in eastern Syria where regime air defense are non-existent. But this would allow ISIS to operate freely in some parts of the country, thereby undermining the stated mission in America’s newest battle theater.

Patrick Megahan is a research analyst at Foundation for Defense of Democracies focusing on military affairs. He manages the website militaryedge.org.